Book excerpt: Was there international law in the Middle Ages? Using treaties as its main source, this book examines the extent to which such a system of rules was known and followed in the period 700 to 1200. It considers how consistently international legal rules were obeyed, whether there was a reliance on justification of action and whether the system had the capacity to resolve disputed questions of fact and law. The book further sheds light on issues such as compliance, enforcement, deterrence, authority and jurisdiction, challenging traditional ideas over their role and function in the history of international law. International law in Europe, 700–1200 will appeal to students and scholars of medieval Europe, international law and its history, as well as those with a more general interest in warfare, diplomacy and international relations.